Crop Protection 3.3 Flashcards
What is the difference between “balanced community” and “monoculture”?
Balance exists in natural ecosystems (variety of species, competition etc)
In agricultural monoculture, there is usually a single crop species cultivated over a large area.
What are the problems with monoculture?
Ideal growing conditions for pests leading to a reduction of yield.
What are weeds?
Plants that grow where they are not wanted and compete with crop plants for resources.
What are the potential effects of weeds?
- Reduction of crop productivity due to competition
- Released chemicals which inhibit growth of crop
- Contaminate grain crops with their seeds
- Act as hosts for diseases and crop pests
What are annual crop weeds?
- Have a rapid growth rate
- Produce flowers quickly and have a short lifecycle
- Produce a large number of seeds
- Have seeds which are viable for long periods of time
What are perennial crop weeds?
- Live for more than two years so are able to compete with crop plants from the start of the season since weed has already established and has competitive adaptations like;
- Possession of storage organs to provide food if growing
conditions aren’t ideal
- Ability to use vegetive reproduction with structures such as
runners
What is a crop pest?
An organism which damages crop plants, this could be the whole plant or just part of the plant.
What are invertebrate pests?
Insects, moluscs and nematode worms
What are plant diseases caused by?
Fungi, bacteria or viruses. Often carried by invertebrates but can also be carried in the soil and air.
Damage crops and reduce plant productivity.
What are cultural methods?
Non-chemical methods of preventing problem organisms from establishing and affecting the crop.
Often require planning and aren’t reactive.
What is ploughing? (cultural method)
A top layer of soil is turned over to bury perennial weeds which then die and decompose.
Removal of weeds (cultural method)
Weeds are removed early in the lifecycle of a crop, enabling the crop plant to gain a head start and be better able to out-compete weeds later.
Crop Rotation (cultural method)
A very different crop is grown in a field in successive years. This prevents the build up of pathogens which may cause an outbreak if the same crop is grown year after year in the same field.
Removal of alternative hosts (cultural method)
Weeds are removed at the edge of the field which may provide food and shelter for pests and vectors
Destruction of crop residue (cultural method)
Straw or stubble can contain fungal pathogens. It can be avoided by removal and/or ploughing
